1. Field of the Invention
This invention relates to the use of starch as a fuel/binder in pyrotechnic compositions, especially those propellants suitable for use in inflating an infltable device, such as a vehicle safety restraint.
2. Description of the Prior Art
Various pyrotechnic propellants have been prepared for generating a gas upon combustion in order to inflate an air bag or similar safety restraint in a vehicle so as to restrain movement of an occupant in the event of a sudden deceleration of the vehicle, such as caused by a collision. In order to be employed as a pyrotechnic gas generating composition for inflatable occupant restraints, several criteria must be met. The pyrotechnic must be capable of producing non-toxic, non-flammable and essentially smokeless gases over a wide variety of temperatures and other environmental conditions. The gases that are generated must be totally ignited at a sufficiently low temperature so as not to destroy the restraint or injure the occupant. The pyrotechnic must also be safe to handle and must be capable of generating a substantial amount of gas within a very short period of time, e.g., less than about 100 milliseconds.
A wide variety of pyrotechnic compositions have been suggested for possible use for inflating vehicle occupant safety restraints. A typical pyrotechnic composition is disclosed in U.S. Pat. No. 3,897,285 to Hamilton et al., and is comprised of a fuel such as carbonaceous material, aluminum or magnesium; and an inorganic oxidizer such as metal chlorate, a metal perchlorate, or a metal nitrate.
Another typical pyrotechnic composition is described in co-pending application Ser. No. 767,726, filed Feb. 11, 1977 and incorporated herein by reference. The pyrotechnic composition disclosed therein is comprised of an inorganic oxidizer such as a metal perchlorate and a highly oxygenated organic binder such as a polyester resin or polyacetal resin.
Although pyrotechnic compositions can be produced using a wide variety of ingredients, to obtain a wide variety of results, there is still a need to develop a fuel/binder which can offer both economic advantages as well as pyrotechnic advantages, such as higher burn rates at lower energy levels.